1. Field of Invention
The invention relates to a method for the emptying of a blood tubing set of a blood treatment device for extracorporeal blood treatment comprising a membrane filter having a first chamber, namely a blood chamber, and a second chamber separated therefrom by a membrane, said first chamber being flowed through by blood in operation of the blood treatment device and said second chamber being flowed through by filtrate in operation of the blood treatment device, and said blood tubing set including an arterial blood tube and a venous blood tube which are both in communication with the first chamber of the membrane filter and which conduct blood from the patient to the membrane filter and from the membrane filter to the patient in operation of the blood treatment device, and comprising a substituate line which opens into the arterial blood tube and/or into the venous blood tube, and comprising a substituate pump which is in communication with the substituate line such that it conveys substituate from a substituate source through the substituate line. The named membrane filter can, for example, be a hemodiafilter or a hemofilter.
2. Description of the Prior Art
Different methods for the emptying of a blood tubing set are known from the prior art. It is known from EP 1 161 271 A1 to operate dialysate pumps located on the dialysate side for the purpose of emptying the blood tubing set such that a pressure drop is adopted over the membrane of the dialyzer by means of which the liquid located in the blood tubing set is transported via the membrane of the dialyzer to the dialysate side, that is into the second chamber, and is removed from there by means of draining lines. A substituate bag is in communication with the blood tubing set and collapses due to the emptying of the blood tubing set or due to the low pressure located therein. As soon as the pressure in the blood tubing set falls below a specific threshold, a valve is opened via which air is sucked into the blood treatment tubing set until the pressure in the blood tubing set corresponds to atmospheric pressure.
The blood pump is in operation during the emptying of the blood tubing set via the membrane of the dialyzer until the liquid has been removed from the blood tubing set.
It is known from EP 0 830 153 A1 to displace liquid from the blood tubing set and also from the dialysate circuit by means of air before the corresponding hose lines are separated from the dialyzer.
Finally, DE 34 42 744 A1 discloses a method in which the liquid in the blood tubing set is displaced with the help of a ring line in the blood tubing set and with the help of an air source. The subject of the patent application is to be able to carry out a leak test or a pressure test on the dialyzer.